ken scharf wrote:

I bought one of these kits to make use of a sample AD9851 chip I got
from Analog Devices a few years ago.

http://www.amqrp.org/kits/dds60/index.html

I knew it was hopeless to bread board something with this chip, but even
with a PC board soldering something with such close lead spacing is a
challenge (especially when you're past 50 with failing close in vision
and less than rock solid stable hands). Still I figured I'd give it a
try. Armed with the smallest soldering tip available for my Weller
PES51 soldering station, a good magnifier lamp AND a binocular
microscope I gave it a try to solder the chip to the board.

Well there is good news and bad news. The bad news is that it is
impossible to solder the chip by hand without creating solder bridges.
The good news is that I did a good enough job to get the chip 99%
perfectly centered on the solder pads, and you can remove the solder
bridges with solder wick without removing the chip from the PC board.

It would have been easier with thiner solder (I had .021" dia solder)
and a thiner soldering iron tip, but inspection with the microscope
shows no shorts, and it looks like all the pins are properly soldered.
Naked eye it doesn't look pretty but it should work.

Now to solder those chip caps and resistors! (They should be easier,
the AD9851 was the worst part to place with the tight spacing, all the
other parts have lead spacing at least twice as wide).


Be sure to more or less "drown" the pins to be soldered with flux. If you
get solder bridges, you probably have to little flux applied - really slob
the flux on the pins. When you think you have enough of flux, add more...

Any bridges are corrected with solder wick.

The AD98xx can be soldered with a 0.5mm ceramic tip. Get one of these cheap
( 10$ ) magnifying visors, especially if you are half blind as I am...

The AD9851 is one of the easiest SMD IC's to solder as there are pins only
on two sides.

Besides... We have been using SMD's since the early eighties now so stop
whinging over it, adapt! They wont go away and they actually improve most
RF designs!

//Dan, M0DFI

On Dec 29, 3:37 pm, Dan Andersson wrote:

Besides... We have been using SMD's since the early eighties now so stop
whinging over it, adapt! They wont go away and they actually improve most
RF designs!

I've seen some suggestions go around that are very similar to hot-air
rework. I just wanted to mention that SparkFun electronics sells some
rework stations cheaply, and has useful tutorials on soldering SMD
parts. Their site: http://www.sparkfun.com

wackyvorlon wrote:

On Dec 29, 3:37 pm, Dan Andersson wrote:
Besides... We have been using SMD's since the early eighties now so stop
whinging over it, adapt! They wont go away and they actually improve most
RF designs!

I've seen some suggestions go around that are very similar to hot-air
rework. I just wanted to mention that SparkFun electronics sells some
rework stations cheaply, and has useful tutorials on soldering SMD
parts. Their site: http://www.sparkfun.com

When you have a proper pc board smt is easy (once you've mastered the
new soldering techniques. I had no problem getting the AD9851 onto the
board. I think the microscopic hairs I'm seeing are a result of using
the solder braid wick. I may have not heated it enough and pulled it
off too soon leaving solder hairs behind. Flux sure does help, and I'll
use plenty when I solder the next few smt ic's down.

I have some smt mounting boards that allow mixing smt parts with through
hole on 100 mil grid proto boards. I fear that the extra long leads
this adds to the smt parts will make rf performance a problem,
especially with 100-400mhz clock signals to the dds chips (AD9951).
I've heard of people designing their own pc boards using laser printer
output and iron on toner for resit. I've tried this before but with
'bleeding' of the toner during application I don't think I can get
better than 50 mil trace separation. Also I've had bad luck etching
boards with very thin traces, the traces get etched away before larger
areas of copper are finished etching. If I try designing boards for SMT
parts I'll probably have to farm them out to a professional house, but
this can be expensive for making but one board. (Unless you plan on
writing a QST article and selling the extra boards....).

All of my first year students can hold 20 mil traces and spaces, the C
students can hold 15 mil, and the really good ones can hold 10.

Jim


I've heard of people designing their own pc boards using laser printer
output and iron on toner for resit. I've tried this before but with
'bleeding' of the toner during application I don't think I can get
better than 50 mil trace separation.

RST Engineering wrote:
All of my first year students can hold 20 mil traces and spaces, the C
students can hold 15 mil, and the really good ones can hold 10.

Yeah, but I'll bet your first year students' eyesight is 30 years
younger than that of the average participant in this NGgrin!

--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com
(I was a first-year student 29 years ago)

On 2006-12-30, ken scharf wrote:
I've heard of people designing their own pc boards using laser printer
output and iron on toner for resit. I've tried this before but with
'bleeding' of the toner during application I don't think I can get
better than 50 mil trace separation.

Print your design on some kind of clay coated paper (people have
used everything from magazine pages to photo paper intended for
inkjets) and look at the print with a loupe. Cheap laser printers
will produce a result full of pinholes. A nice Xerox will make a
good, solid black. I haven't had any trouble with toner melting
or running. In fact, once you transfer it onto the PCB it's hard
to get off!

If I try designing boards for SMT
parts I'll probably have to farm them out to a professional house, but
this can be expensive for making but one board. (Unless you plan on
writing a QST article and selling the extra boards....).

You've got to pick the right board house for each order. Some, like
batchpcb.com, are particularly cheap if you want few, small boards.
They don't have setup fees or even per-board fees, only a per-order
charge. But their $2.50/in^2 grows faster than some other places
which have bigger minimum size boards/minimum orders.

--
Ben Jackson AD7GD

http://www.ben.com/

On Sun, 31 Dec 2006 04:22:42 -0600, Ben Jackson wrote:

You've got to pick the right board house for each order. Some, like
batchpcb.com, are particularly cheap if you want few, small boards.
They don't have setup fees or even per-board fees, only a per-order
charge. But their $2.50/in^2 grows faster than some other places
which have bigger minimum size boards/minimum orders.

I have been using an off-shore fab for years and they seem to do just what i
want, but have setup fees that make protos expensive. So I went and looked at
batchpcb.com but they do mention a $US10 setup fee in their FAQ.

http://www.batchpcb.com/faq.php?osCs...a389ad75decda8

Do they actually charge it?

On 2006-12-31, quandong nut wrote:
I have been using an off-shore fab for years and they seem to do just what i
want, but have setup fees that make protos expensive. So I went and looked at
batchpcb.com but they do mention a $US10 setup fee in their FAQ.

http://www.batchpcb.com/faq.php?osCs...a389ad75decda8

Do they actually charge it?

There's a $10 fee per order. But it's not per board or even per design.
It's more like a "shipping and handling" fee. So if you keep some boards
on file with them you can always throw in a few (smt adapters, or proto
boards) with another order for only the sq in cost.

--
Ben Jackson AD7GD

http://www.ben.com/

Ben Jackson wrote:
On 2006-12-30, ken scharf wrote:
I've heard of people designing their own pc boards using laser printer
output and iron on toner for resit. I've tried this before but with
'bleeding' of the toner during application I don't think I can get
better than 50 mil trace separation.

Print your design on some kind of clay coated paper (people have
used everything from magazine pages to photo paper intended for
inkjets) and look at the print with a loupe. Cheap laser printers
will produce a result full of pinholes. A nice Xerox will make a
good, solid black. I haven't had any trouble with toner melting
or running. In fact, once you transfer it onto the PCB it's hard
to get off!

If I try designing boards for SMT
parts I'll probably have to farm them out to a professional house, but
this can be expensive for making but one board. (Unless you plan on
writing a QST article and selling the extra boards....).

You've got to pick the right board house for each order. Some, like
batchpcb.com, are particularly cheap if you want few, small boards.
They don't have setup fees or even per-board fees, only a per-order
charge. But their $2.50/in^2 grows faster than some other places
which have bigger minimum size boards/minimum orders.

My problem with the iron on transfers wasn't being able to print thin,
close spaced lines on to the transfer medium. The problem was that when
ironed on the toner lines 'spread out' so adjacent lines touched. Also
a problem was timing just how long to leave the board in the soup to
etch. I did heat the etchant up first and used an IR lamp to try and
keep it warm, but even so the thin close spaced traces were close to
being over etched long before larger and wider spaced traces were
'done'. (maybe a problem with 'Radio Shack' etchant?)